Inert Gas Drying of Bulk Material
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Solution Overview
Problem
Conventional convective drying methods for bulk materials, especially agricultural products, face challenges such as high energy costs, microorganism activation leading to spoilage, and inefficient drying of crops with high harvest moisture content, resulting in quality losses and pest infestation.
Innovation Solution
A method involving a cooling step followed by convective drying in a gas-tight container using an inert gas mixture of nitrogen, carbon dioxide, and a noble gas, which absorbs moisture and is heated to optimize drying temperatures, reducing microbial growth and energy consumption through heat recovery and process heat recycling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional convective drying methods are used with heated air, then drying speed is improved, but energy consumption increases and microorganism activation occurs leading to spoilage
Solution Approach 1:
The patent applies inert atmosphere by replacing heated air with heated inert gas (nitrogen, carbon dioxide, or noble gases) as the drying medium. This eliminates oxygen that activates microorganisms while maintaining the convective drying mechanism. The inert gas absorbs moisture from bulk materials through convection and is subsequently condensed and removed, achieving rapid drying without microbial spoilage.
2Productivity
If high temperatures are used for drying, then drying efficiency is improved, but quality losses and biochemical degradation increase
Solution Approach 1:
The patent changes the chemical composition parameter of the drying gas from oxygen-containing air to inert gases (nitrogen, carbon dioxide, or noble gases). This parameter change prevents oxidative biochemical degradation and microorganism activation while allowing efficient moisture removal through convection and subsequent condensation of the inert gas-vapor mixture.
3Loss of time
If rapid drying is performed to meet storage requirements, then storage preparation time is reduced, but energy consumption increases
Solution Approach 1:
The patent utilizes phase transitions in two stages: first, moisture evaporates from bulk materials into the inert gas phase; second, the inert gas-vapor mixture is condensed back to liquid water and removed. This phase transition mechanism enables rapid moisture removal with efficient energy utilization, as the condensation process recovers heat that would otherwise be lost.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables efficient, energy-saving drying with reduced quality losses and microbial growth, allowing for weather-independent storage and preservation of bulk materials by maintaining the biological value of the products.
Implementation Method 1
the bulk material to be dried is surrounded by a gas mixture which absorbs water contained in the bulk material to be dried
Implementation Method 2
a cooling step is carried out before the drying step, in which the bulk material is brought to a temperature lower than the ambient temperature
Implementation Method 3
the gas mixture is heated via a first heat exchanger connected to a hot water storage tank
Implementation Method 4
The cooled air is then supplied to the grain mass in the grain store to cool the grain
Data Source
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AI summary
The invention relates to a method for convectively drying bulk material in a container (1). A gas mixture flows around the bulk material to be dried in the container (1) in a drying step, said gas mixture absorbing water contained in the bulk material to be dried and subsequently being discharged out of the container (1). A cooling step is carried out prior to the drying step, wherein the bulk material is brought to a temperature below the ambient temperature. Both the cooling step as well as the drying step are carried out in the same gas-tight container (1).